Problem: Nadia did 9 more jumping jacks than Stephanie in the evening. Nadia did 79 jumping jacks. How many jumping jacks did Stephanie do?
Explanation: Nadia did 79 jumping jacks, and Stephanie did 9 fewer than that, so find the difference. The difference is $79 - 9$ jumping jacks. She did $79 - 9 = 70$ jumping jacks.